Multics

operating system /muhl'tiks/ MULTiplexed Information and

Computing Service. A time-sharing operating system

co-designed by a consortium including MIT, GE and BellLaboratories as a successor to MIT's CTSS. The system

design was presented in a special session of the 1965 Fall

Joint Computer Conference and was planned to be operational in

two years. It was finally made available in 1969, and took

several more years to achieve respectable performance and

stability.

Multics was very innovative for its time - among other things,

it was the first major OS to run on a symmetricmultiprocessor; provided a hierarchical file system with

access control on individual files; mapped files into a

paged, segmented virtual memory; was written in a

high-level language (PL/I); and provided dynamic

inter-procedure linkage and memory (file) sharing as the

default mode of operation. Multics was the only

general-purpose system to be awarded a B2 security rating by

the NSA.

Bell Labs left the development effort in 1969. Honeywell

commercialised Multics in 1972 after buying out GE's computer

group, but it was never very successful: at its peak in the

1980s, there were between 75 and 100 Multics sites, each a

multi-million dollar mainframe.

One of the former Multics developers from Bell Labs was KenThompson, a circumstance which led directly to the birth of

Unix. For this and other reasons, aspects of the Multics

design remain a topic of occasional debate among hackers. See

also brain-damaged and GCOS.

MIT ended its development association with Multics in 1977.

Honeywell sold its computer business to Bull in the mid

1980s, and development on Multics was stopped in 1988 when

Bull scrapped a Boston proposal to port Multics to a

platform derived from the DPS-6.

A few Multics sites are still in use as late as 1996.

The last Multics system running, the Canadian Department of

National Defence Multics site in Halifax, Nova Scotia, Canada,

shut down on 2000-10-30 at 17:08 UTC.

The Jargon file 3.0.0 claims that on some versions of

Multics one was required to enter a password to log out but

James J. Lippard [email protected], who was a Multics

developer in Phoenix, believes this to be an urban legend.

He never heard of a version of Multics which required a

password to logout. Tom Van Vleck [email protected]

agrees. He suggests that some user may have implemented a

'terminal locking' program that required a password before one

could type anything, including logout.

Home .

Usenet newsgroup: news:alt.os.multics.

[Jargon File]

(2002-04-12)